a, \(\left(\frac{1}{3}-\frac{1}{2}\right)^x-1=\frac{1}{36}\)
=> \(\left(\frac{-1}{6}\right)^x=\frac{1}{36}+1\)
=> \(\left(\frac{-1}{6}\right)^x=\frac{37}{36}\)
vì ko có số nào mũ với \(\left(\frac{-1}{6}\right)=\frac{37}{36}\) => x ko tồn tại
b, \(\frac{25}{5}^x=\frac{1}{125}=>5^x=\frac{1}{125}=>5^x=5^{\frac{1}{125}}\)
=> x = \(\frac{1}{125}\)
Bạn ơi đề là \(\left(\frac{1}{3}-\frac{1}{2}\right)^{x-1}=\frac{1}{36}\) hay \(\left(\frac{1}{3}-\frac{1}{2}\right)^x-1=\frac{1}{36}\) vậy.
\(\left(\frac{1}{3}-\frac{1}{2}\right)^{x-1}=\frac{1}{36}\)
\(\Rightarrow\left(-\frac{1}{6}\right)^{x-1}=\frac{1}{36}\)
\(\Rightarrow\left(-\frac{1}{6}\right)^{x-1}=\left(\frac{1}{6}\right)^2\)
\(\Rightarrow x-1=2\)
\(\Rightarrow x=3\)
b)\(\frac{25}{5^x}=\frac{1}{125}\)
\(\Rightarrow\frac{25}{5^x}=\frac{25}{3125}\)
\(\Rightarrow\frac{25}{5^x}=\frac{25}{5^5}\)
\(\Rightarrow x=5\)
Bài 1:
a) \(\left(\frac{1}{3}-\frac{1}{2}\right)^{x-1}=\frac{1}{36}\)
=> \(\left(-\frac{1}{6}\right)^{x-1}=\frac{1}{36}\)
=> \(\left(-\frac{1}{6}\right)^{x-1}=\left(\frac{1}{6}\right)^2\)
=> \(x-1=2\)
=> \(x=2+1\)
=> \(x=3\)
Vậy \(x=3.\)
Còn câu b) bạn Nguyễn Kim Hưng làm rồi nhé.
Chúc bạn học tốt!